Oswald Külpe (August 3, 1862 – December 30, 1915) was one of the structural psychologists of the late 19th and early 20th century. He was born at Kandau, Courland in what is now Latvia. In 1879 he graduated from the Gymnasium at Libau, where he taught for the next two years. He was influenced strongly by his mentor Wilhelm Wundt, but later disagreed with Wundt on the complexity of human consciousness that could be studied.

Külpe was a student of history at the University of Leipzig when he encountered Wundt and decided to change his major to work with Wundt. When he graduated he became Wundt's assistant.

However, he became somewhat impatient with the strictures that Wundt had placed on what could and could not be studied and, after leaving Leipzig for the University of Würzburg, he began to practice what he called systematic experimental introspection. His subjects would complete complex tasks and then provide a retrospective account of their cognitive processes during the task.

His main finding, known as "imageless thought" seemed to be that thoughts can occur without a particular sensory or imaginal content.